Types of Operating System

types of operating systems: a brief introduction

1. DISCOVER . LEARN . EMPOWER Introduction to Operating System APEX INSTITUTE OF TECHNOLOGY Bachelor of Engineering (Computer Science & Engineering) OPERATING SYSTEM Instructor: M s Akansha Moral

2. Content 1. Types of operating system 2. Serial Processing Operating System 3.Batch Operating system 4.Multi-programming Operating System 5.Distributed Operating System 6.Network Operating System 7.Real Time Operating System 8.Multi processor Operating System

3. Types of Operating System There are many types of operating systems that can be listed to study the types the operating systems. Serial Processing Operating System Batch Operating system Multi-programming Operating System Time Sharing System Distributed Operating System Network Operating System Real Time Operating System Multi processor Operating System

4. Serial operating System Serial Processing : The Serial Processing Operating Systems are those which Performs all the instructions into a s sequence Manner or the Instructions those are given by the user will be executed by using the FIFO Manner means First in First Out. . In this the Program Counter will determines which instruction is going to Execute and the which instruction will be Execute after this. Mainly the Punch Cards are used for this. Problem : the Main Problem is that a user doesn’t interact with the System while he is working on the System, means the user can’t be able to enter the data for Execution.

5. Batch Operating Systems The Batch Processing is same as the Serial Processing Technique. But in the Batch Processing Similar Types of jobs are Firstly Prepared and they are Stored on the Card. According to the concept of the batch operating systems, it states that until a JOB (or process) has been completely processed and has been successfully executed, we cannot perform another job or process at the same time. The very first concept which denoted the task to be performed by the operating system was the concept of Job. A job is defined as a piece of work done on a computer. It generally consists of the program along with the data . Let’s consider a scenario where , and are different jobs that are supposed to be assigned to the batch operating system. All the three jobs cannot be run, processed and executed at the same time as per the concept of this kind of a system.

6. If the input/output is required, the gets transferred from the main memory to fulfilled the requirements of the same. At this time the main memory remains empty. The job gets successfully executed after the requirements of the input and output are fulfilled. Therefore there is no user interaction involved in such systems. Such jobs that run without the end user interaction are called BATCH JOBS. Example for a batch job can be the program that reads a large file and gives out a report. Batch processing is basically done for those frequently used programs that could be run with minimal human interaction. ADVANTAGES The following are the advantages of using a batch operator: Reduction of manual work. Fast and well managed execution. Reduction in the repetitive usage of the punch cards and magnetic tapes. Reduction in CPU’s idle time. Batch Operating Systems

7. The following are the disadvantages of the batch operating systems: SEQUENTIAL EXECUTION: Jobs in a batch system are always executed sequentially. STARVATION: Different jobs might take different amount of time for execution which leads to the starvation of some of the jobs. Disadvantages

8. Multi programming Operating System As we know that in the Batch Processing System there are multiple jobs Executed by the System. The System first prepares a batch and after that he will Execute all the jobs that are Stored into the Batch. But the Main Problem is that if a process or job requires an Input and Output Operation, then it is not possible and second there will be the wastage of the Time when we are preparing the batch and the CPU will remain idle at that Time. Multi-Programming we can Execute Many Programs on the System and When we are Working with the Program then we can also Submit the Second or Another Program for Running and the CPU will then Execute the Second Program after the completion of the First Program. And in this we can also specify our Input means a user can also interact with the System. •

9. Memory Layout for Multiprogrammed System Image no : 1 Image reference : https://tse3.mm.bing.net/th?id=OIP.aqJD5BUuuT5K5diDhhgxnAHaJk&pid=Api&P=0&w=300&h=300

10. Time Sharing System These types of systems are also known by many other names such as multitasking operating systems, fair share operating system, multi-programming (Round Robin Technique) etc… The main idea behind a time sharing operating system can be explained with an example. Consider an example where a processor is undergoing some process for execution. During the process of execution, if the processor wants to wait for an I/O or for any other event, then at that time why should the CPU remain idle? In such situation, the CPU switches over to some other and starts running it. In case, if again the processor waits, the CPU again switches over to some other process and the process goes on. The main idea which could be understood from this context is that, the CPU should not remain idle and should remain busy in performing one or more number of tasks at the same interval of time.

11. Time Sharing System One important thing to be noted here is that when the process volunteers to wait for some event, the CPU switches over to some other task. We do not force the CPU to leave the existing task and switch over to the other one. The process itself wants to perform some task which is not related to the CPU and hence it switches over to some other process. It maintains the working of all the systems simultaneously. As the name suggests, the time is being equally shared for all the processes. Hence, multi-tasking is multi- programming with time sharing. The various tasks are scheduled to access the CPU for a fixed time limit known as the time quantum . The switching of CPU among various processes is so rapid that it gives us an illusion of all processes working at the same time.

12. Advantages of Time sharing system The following are the advantages of using the time sharing operating systems: Reduced response time. Reduced CPU’s idle time. It avoids the duplication of the software.

13. Disadvantages of Time sharing system The following are the disadvantages of the time sharing operating systems: The integrity and security of a user’s program is a doubt. Problem of reliability. Problem of data communication.

14. Distributed operating System A distributed operating system is a kind of system which uses MULTIPLE CENTRAL PROCESSORS. This is done in a motive of serving multiple real- time applications and multiple users. These processors get the distributed amount of data processing jobs accordingly. Consider an example in which a company has a lot of systems but has only one printer. All the members of the company want to take the printouts at the same time. This distributed operating system provides the users the access to that printer using different systems. This is possible only when all the systems of the company are linked together by a single communication network. Linking the systems does not mean that the data of each system is being shared with each other, it rather means that when a task is to be performed, it could be performed using any of the given systems in order to enhance the pace of work .

15. ADVANTAGES The following are the advantages of using the distributed operating systems: A user at one site could get an access to the resource which is available at another site using this resource sharing facility . The speed of data exchange with one another could be enhanced by using email. Also even if one site of work encounters a failure, the remaining sites still potentially remain operating. It also helps in reduction of the load on the host computer. Data exchange process within the network is fast and reliable.

16. The following are the disadvantages of the distributed operating systems: The entire communication relies upon a single network and hence failure in this network will result in the failure of the entire communication. The language used to establish the distributed systems are not well defined yet. This kind of a system is very expensive and it is not readily available as the underlying software of this system is highly complex. DISADVANTAGES

17. Network operating System The network operating system is similar to distributed operating system when their architecture is concerned. This type of a system is a system that runs upon a server and provides the server the ability to manage the applications, security, users, data and other networking functions. The main motive of this kind of a system is to allow shared file and printer access to multiple computers in a network. The multiplicity of computers is known in such types of systems whereas in distributed type of operating systems, the multiplicity is unknown. All the works to be accessed are dependent upon the server and hence the work is done manually through the server. The drawback of these kinds of systems is that if any part of the server’s hardware encounters a problem, then all the systems will get affected whereas this is not the case in a distributed operating system.

18. Network operating System The following operating systems are the examples of the network operating system: WINDOWS SERVER 2003 LINUX MICROSOFT WINDOWS SERVER 2008 UNIX MAC OS X ETC… ADVANTAGES OF NETWORK OPERATING SYSTEM The following are the advantages of using a network operating system: The security of the system is managed by the server. The servers are centralized servers and are highly stable. The upgrades to new technologies and hardware can be easily integrated into the system. The elements can be replaced when the need increases.

19. These systems are quite expensive. The malfunctioning of the server affects the whole communication and hence the entire network gets affected. Disadvantages of the network operating systems

20. Real Time operating System These types of operating systems are the types of those operating systems which do not perform buffering delays. These operating systems are intended to serve the real time applications. The deadline of a work is already fixed and hence the chances of delays in such systems are negligible. The real time operating system fails if it is not well defined or it does not have a fixed time constraint .

21. APPLICATIONS They are used in the scientific experiments. Medical imaging systems Industrial control systems Weapon systems Air traffic control systems Robots Thermal power plants etc… The applications of such systems can easily help us to figure out the reasons of having no buffering delays in real time operating systems .

22. Based upon the strictness of the time constraints, the real time operating systems can be classified as follows: HARD REAL TIME SYSTEMS SOFT REAL TIME SYSTEMS CLASSIFICATION

23. These types of real type systems are the systems which strictly follows the definition of a real time system. The time constraints are strictly followed here and hence no delays are accepted. EXAMPLES The following are places where the time constraints are strictly followed: Submarine signaling RADAR Air traffic control systems Delays in the signaling of such systems are proved to lead hazardous accidents. HARD REAL TIME SYSTEMS

24. SOFT REAL TIME SYSTEMS These types of systems are the systems which are less strict when compared to the hard time real systems and hence a little bit delay could be accepted. EXAMPLES : The following are the examples of the soft real time systems: Multimedia Virtual reality Video conferencing etc…

25. Multi processing System Generally a Computer has a Single Processor means a Computer have a just one CPU for Processing the instructions. But if we are Running multiple jobs, then this will decrease the Speed of CPU. For Increasing the Speed of Processing then we uses the Multiprocessing, in the Multi Processing there are two or More CPU in a Single Operating System if one CPU will fail, then other CPU is used for providing backup to the first CPU. With the help of Multi- processing, we can Execute Many Jobs at a Time. All the Operations are divided into the Number of CPU’s. if first CPU Completed his Work before the Second CPU, then the Work of Second CPU will be divided into the First and Second.

26. REFERENCES “ Galvin, Peter B., Silberchatz, A., “Operating System Concepts”, Addison Wesley, 9th Edition. William Stallings, Operating Systems: Internals and Design Principles, 7th edition Pearson Education Limited, 2014 ISBN: 1292061944, 9781292061948. Andrew Tananbaum, “Operating System”, PHI Learning. Godbole, Kahate, "Operating System: A Concept Based Approach", Tata Mc-Graw- Hill.

27. E-Video Links https://www.youtube.com/watch?v=bkSWJJZNgf8&list=PLxCzCOWd7aiGz9donHRrE9I3Mwn6XdP8p https://www.youtube.com/watch?v=vBURTt97EkA&list=PLBlnK6fEyqRiVhbXDGLXDk_OQAeuVcp2O https://nptel.ac.in/courses/106/108/106108101/

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